Energy-saving receivers are applied in many technical fields. For example, such receivers are applied for monitoring objects and can be an integral part of a system of radio nodes or sensor nodes. Known energy-saving receivers which for example are realised as super-regenerative receivers or detector receivers, have current uptakes which lie at a few hundred microamperes and their sensitivity is moderate to low. Such receivers are particularly suitable for a communication with low data rates, e.g. data rates <10 kbps.
A wake-up receiver is known from US 2008/0108318 A1 and is designed as a sampling receiver, i.e. the receiver is switched on and off with a constant sampling rate by a control unit, wherein the received signal during the sampling pulse is transferred to a digital receiver which produces a data sequence. If the data sequence corresponds to a predefined wake-up signal, a main receiver is switched on. According to the example cited there, the switch-on time is 2 μs, and the sampling period is 50 μs (20 kHz). The current consumption of the known receiver in the permanently switched-on condition can for example be assumed to be at 10 mA, which is the common current consumption of commercial receiver circuits. The average current consumption thus results at 400 μA, which however still consumes too much energy, in order to permit a year-long battery operation. Thus with a lithium button cell CR 2032 (210 mAh charge) thus a maximal operating duration of 20 days can be achieved.